1. Field of the Invention
The present invention relates to the aerial deployment of objects, particularly the deployment of munitions, and more particularly to the deployment of line charges for obstacle breaching.
2. Description of the Related Art
Overcoming military obstacles such as wire obstacles and anti-personnel mines is of great importance during military operations. Over the years, systems involving explosive charges have been developed to clear minefields. More recently, rocket-deployed line charges have been developed for obstacle breaching. In most of these line-charge systems, explosive charges are connected by a strength member such as ropes, and a rocket motor at one end of the line charge drags the line charge aerially onto the obstacle. The explosive charges are then detonated to clear a path through the obstacle.
Examples of such obstacle breaching systems are seen in the following U.S. Patents. U.S. Pat. No. 4,683,797, to Wittbrodt, entitled LINE CHARGE DETONATION INTERLOCK ASSEMBLY, discloses a military system for clearing a path through a minefield, including a rocket launched flexible line and associated explosive blocks.
U.S. Pat. No. 4,823,672, to Eidelman, entitled APPARATUS AND METHOD FOR NEUTRALIZING MINEFIELDS, describes a rocket launched apparatus including strands of explosive charge detonated by explosive cord. The strands are rolled and covered by a plastic casing.
U.S. Pat. No. 5,675,104, to Schorr et al., entitled AERIAL DEPLOYMENT OF AN EXPLOSIVE ARRAY, describes an apparatus in which an array of charges are connected by strapping and detonation cord.
U.S. Pat. No. 5,959,233, to Garcia et al., entitled LINE CHARGE FASTENER AND DETONATING CORD GUIDE, describes deployable ammunition for clearing mine fields in which a detonating cord extends through bores of explosive charges. The detonating cord may slide through the bore to avoid strain failure during launch. A fabric sleeve encases the explosive charges and the detonating cord between the charges.
U.S. Pat. 5,960,732, to Peterson, entitled LINE CHARGE DEPLOYMENT APPARATUS, describes a fine charge deployable from a watercraft. The line charges are attached by a detonator cord/strength member.
One system which has already been deployed is the Anti-Personnel Obstacle Breaching System, APOBS MK7, Mod 1, which is described in document http://www.ncsc.navy.mil/CSS/Projects/apobs/apobs_paper/combo3.htm. This system includes a rocket motor and front fuze assembly, a front backpack assembly containing 60 fragmentation grenades spaced along a 25-m detonating cord and nylon rope line charge assembly, a rear backpack and rear fuze assembly containing 48 fragmentation grenades spaced along a 20-m detonating cord and nylon rope line charge assembly. Here the nylon ropes are the strength members.
The deployable line charges generally use detonating cord to detonate the individual charges, and an important consideration in the design of deployable line charges is the stress to the detonating cord during deployment. The tensile strength during deployment is generally carried by a strength member connecting the explosive charges so that the detonating cord is not stressed, and stress to the detonating cord can be avoided by providing excess (slack) detonating cord to allow for lengthening of the strength member during deployment.
Recently, an improvement to the APOBS system has been proposed in which the nylon rope strength member assembly is replaced with an overbraided fabric sleeve. Braiding is a fiber placement technique which results in a tubular braided fabric with unique fiber architecture as opposed to other fabric forming methods such as weaving. In particular, the process of overbraiding, that is, forming the braid around the object to be covered, has particular advantages. Among these advantages are the elimination of bands used to clamp the nylon ropes to the explosive charges, better protection of the detonating cord from damage upon landing, better tensile performance of the strength member and, concomitantly, better flight characteristics.
However, during the overbraiding of a line charge of explosives and detonating cord, it is difficult to provide excess detonating cord between the individual explosive charges while keeping the proper separation between the explosive charges.
Moreover, it is desirable to make sure that the excess detonating cord lies flat and is neatly stowed in the braided sleeve. Eventually, the braided sleeve is folded as the line charge is packed in the backpack from which the line charge is deployed, and this folding is best performed if the sleeve may be folded flatly.
Therefore, based on our reading of the art, we have decided that what is needed is an improved arrangement for providing excess detonating cord in a deployable device. Such a system by should allow for overbraiding but not interfere with the providing of slack in the detonating cord.